In an installation for spraying a coating product, it is known to supply one or several manual or automatic sprayers with a pressurized coating product, as well as with air for spraying this coating product. To that end, it is known to use a pump capable of delivering both pressurized air and pressurized coating product. In some cases, there may be several sprayers. In this case, each sprayer can be supplied by a hose with a different length and/or diameter. In this type of installation, in order to have the same flow rate for each sprayer, pressure regulators are mounted on the pump or the part of the pump that delivers the pressurized coating product. The regulators are used to avoid or limit pressure fluctuations in a hose supplying the sprayer with coating product and to adjust the pressures in each hose independently, in order to obtain an iso-pressure at each sprayer.
Some coating products, like those used to apply a color on wood, are very liquid, i.e., have a particularly low viscosity, close to that of water. To apply such coating products, the supply pressure of the spraying area of a sprayer must be low, in particular below 0.5 bars. Under these conditions, a volume provided inside the body of a sprayer to supply this spraying area most in turn be at a low pressure. This involves supplying the sprayer with a low-pressure coating product, which causes the regulator to operate outside its nominal pressure range, to the point that it is no longer effective and no longer makes it possible to hide travel inversions of the pump. This results in pressure fluctuations in the supply hose of the sprayer, which leads to an irregular application of the coating product.